Astronomik UHC Filter

Astronomik UHC Filter


In stock - Shipped 1-2 working days.

Model:  ak_uhc_125
Part Number:  8H0011
Brand:  Astronomik


The Astronomik UHC is THE filter for visual observing.

The Astronomik UHC (Ultra High Contrast) filter allows the transmission of nearly 100% of the radiation from both O-III and the H beta lines. Though the second window for the H-alpha-line is not intended for visual observing, it is important, if the filter is used with an electronic device. All annoying, scattered light from other wavelength sources, including local artificial light pollution, is reliably filtered out. With this strong blocking of the sky background an unexpected wealth of detail becomes visible for gas nebulae and planetary nebulae.


  • Nearly 100% transmission of O-III & H-beta
  • 96% transmission of H-alpha
  • Blocks most annoying artificial light pollution wavelengths
  • Ideal all-round deep sky filter even for small telescopes
  • Not sensitive to high humidity or ageing effects
  • Scratch-resistance!
  • Excellent quality substrate, diffraction limited - the optical performance of your telescope will not be reduced
  • Parfocal with other Astronomik filters
  • 1mm Glass Thickness
  • Supplied in a high-quality, long lasting, filter box

Main use

Astronomik UHC filters’ astounding high light transmission brings better views of deep-sky-objects even to small telescopes! The high transmission of Astronomik optical glass filters means that enough light is available to allow successful visual observations with telescopes beginning at 2" (50mm) aperture.

Astronomik filters are optimised for use with telescope focal length f / ratios of f/4 to f/15.

Transmission losses and chromatic distortions, which arise with other filters, only occur with Astronomik filters when extremely bright aperture ratios of 1:2 and more come into play.

Another major advantage of the Astronomik UHC filter is the high optical quality of the filter glass. When using Astronomik UHC filters you will quickly notice the same needle-sharp stars which you are familiar with from your astronomical instrument without any filter!

Transmission Chart

  • The horizontal axis is the Wavelength in Nanometers (nm). 400nm is deep blue, at 520nm the human eye senses green and at 600nm red. At 656nm is the famous "H-Alpha" emission line of hydrogen.
  • The transmission in % is plotted on the vertical axis.
  • The blue line shows the transmission of the filter.
  • The most important emission lines from nebulas are shown in orange. The most important lines are from ionised Hydrogen (H-alpha and H-beta) and double ionised oxygen (OIII).

The major emission lines of artificial light pollution:
| Hg 435,8nm | Hg 546,1nm | Hg 577,0nm | Hg 578,1nm |
| Na 589,0nm | Na 589,6nm | Na 615,4nm | Na 616,1nm |

The major emission lines of nebulas:
H-β 486,1nm | OIII 495,9nm | OIII 500,7nm | H-α 656,3nm


  • Visual observation (dark skies): Very good, for telescopes of all apertures and high exit pupil
  • Visual observation (urban skies): Very good, for telescopes from 100 mm aperture
  • Film photography: Reasonable, but very long exposure time
  • CCD photography: Good, when used with an additional IR-block-filter
  • DSLR photography (original): Good, colour balance shifted but contrast enhanced
  • DSLR photography (astro modified): Very good, colour balance is near perfect
  • DSLR photography (MC modified): Good, when used with an additional IR-block-filter
  • Webcam / Video (Planets): Unsuitable
  • Webcam / Video (Deep Sky): Good, if light pollution is a big problem

Technical Data

  • Transmission of nearly 100% of O-III and H-beta
  • Transmission of 96% of H alpha
  • Entire Blocking of annoying wavelengths
  • Ideal All-round Deep Sky filter even for small telescopes
  • Scratch-resistant!
  • Excellent carrier material. The optical performance of your telescope is not reduced by the filter in any way.
  • Parfocal with other Astronomik filters
  • Glass thickness: 1mm
  • Completely resistant against high humidity, scratches and ageing effects
  • Diffraction limited, the filter will not reduce the optical performance of your telescope!
  • Astronomik filters are delivered in a high-quality, long lasting, filter box


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